Hi guys,

I'm having a problem with my 2004 RX8. I've had it 5 years now and it's done 25,000 miles in its lifetime.

When I start a motorway run (65-70mph), the overheat light comes on. Oil pressure and water temperatures are at normal levels. Backing off the gas does not solve the problem. The only way to get rid of this light is to fully press the clutch pedal for a few seconds, letting the car coast.

If I let the car idle on the driveway, the light does NOT come on, which makes me think it's not a mechanical problem, ie, the car's ability to keep itself cool is fine/no radiator issue(?).

I do have a problem when I stop to fill up with petrol and then restart the engine - it struggles/sometimes doesn't start unless it's been left to cool down for 10 minutes (impossible to do at a busy petrol station, so I find myself going to fill up at obscure times in the night when it's quiet).

Radiator levels are topped up, oil is new and clean, and petrol is the correct grade.

I always make sure it's warm before shutting the engine off (temperature gauge at least 1/4), and take it for minimum 20 minute drives.

The light only comes on when I start a motorway run, performance seems unaffected.

Any suggestions?

Thanks
Karl

 

There isn't actually an 'overheating light' I am guessing that you are seeing the low coolant light. If the coolant level is actually fine, then you just have one of the common coolant level sensor failures. Very common for our cars. Only repair option is to replace the coolant bottle.

Hard warm starts is usually the hallmark of failing compression in the engine. Get a compression test to be sure. At 25,000 miles though, it would be REALLY early in it's life to start suffering from compression problems, however as a 2004 if it got driven that little it may not have had MSP-16 done to it, which is very much needed. Chances are your seals are fine, and they are overly carbon caked, which is fixable relatively easily.

 

lemme add something, not all coolant bottle(mazda calls it tank, overflow) has non replaceable sensor, i think its replaceable after revision g, but if urs is 2004 chances are u have a revision a to c. so yea, replace it. or just unplug the sensor plug all together, by doing so you will NEVER see the red little light, but u better check ur coolant level every so often.

hard start when hot could be either low compression or you might still be running the pathetic early starter. replace it with a newer, 2007+ model year that has 2 kw rating will help, and as for msp16, i dont think it helps much since we all know how the apex seal dies in s1 rx8. its a bandaid for a gun shot wound.

 

Sorry, yep, just Googled the image, it is indeed the coolant light. I made sure to check the coolant levels and they are high. Glad to hear it's a sensor fault, but strange that a clutch press fixes it!

The engine was flooded back in January 2011 when I tried a cold start in winter and hadn't driven it for a few weeks. I replaced the battery and it's not had an issue of that nature since - I make a habit of taking it out regularly now to keep it ticking over. Also the nature of UK driving, we spend most our time in stop-go traffic... It sounds like this could all be a contributing factor to this issue as you mentioned a carbon build up?

I've read that warm start problems could be ignition coil problems, so paired this with the "low coolant" to wonder if the coils were being baked, but do you think that is a red herring?

Regarding the MSP-16 (I'm in UK), would/should this have been done automatically by the dealer in its service history? I've always historically taken it to a Mazda dealership to have it serviced. In light of this, if it's not been done, should they still do it for free considering it's something that *should* have been done under warranty automatically?

Also, if I've now got an engine problem because of this, would I have any grounds for complaint with Mazda for not doing what they should within warranty?

You said that the carbon buildup is easy to fix. I'm assuming this isn't by stripping the engine down as many threads are suggesting? Would this be done with Seafoam (I'm in UK so would struggle to get hold of it)? Also someone else has suggested steam cleaning the engine with WD-40 & water in another old thread (which I can get easily in UK - I'm looking at a bottle on my desk now)... but that requires an ECU controller which I don't have...

Also noticed the DIY thread DIY: Mazda Zoom Power Engine Cleaner. This is from 2008 though, and I wondered if it was still valid and safe to do?

Thanks for your time on this - I know there's a lot of different threads and opinions on carbon cleanup, but with so much contradicting info, could you please give me your opinion on which is cheapest, and most effective for my (suspected) circumstances?

Thanks
Karl

 

I love the "cover your eyes and pretend it's not there" approach I'll probably just leave it connected for now - it doesn't cause me any bother now I know it's just likely a sensor bug. It'll encourage me to keep checking anyway!

Are you saying I'm probably best selling the car before it just packs in? Would your DIY cleaning guide be worthwhile in my situation?

Thanks
Karl

 

i would put my bet on shitty starter than low compression. no u dont have to sell the car, if u do, i wouldnt mind to get it from ya for free

 

So far I'm contemplating: New plugs, new coils, new starter. Not a cheap DIY

Performance-wise whilst started and idle... it's got a nice happy steady purr. Acceleration is smooth and responsive. Immediate snappy response when twitching the pedal. Brakes feel good.

All things considered it's a beaut to drive still, heads always seem to turn, friends love it (and abuse me for the lack of mpg, but I always tell them I'd rather pay 35p a mile for the joy of driving it!).

So, with everything considered and the history... 8 years old, 25,000 miles, full service history, 1 major flood (took 3 days to deflood and at the end of it I descaled the plugs), and the fact it's a 2004 (probably mechanically untouched)... would your best guess be just a crappy starter motor?

Obviously I want it running to the level where I'm not crossing my fingers every time I try to start it! With all this in mind (and I know there's a lot of theories and suggestions in other threads - which I have been reading and digesting over the last few weeks before starting this thread - , but that ranges from tearing the engine apart, to using an ECU reset, to getting a new engine, using seafoam, Mazda cleaner, touching nipples, changing plugs, coils, and cats....), what would your educated opinion suggest that I do to get it remedied?

So far I understand my options as: plugs, coils, engine flush, starter, but that's all pretty diverse and expensive, so I want to tackle the cheaper and most probable route (and all the options out there are confusing me!!)!

Even if I gave you the car for free, it'd cost a few quid for a US import and conversion (ps, not happening, and even if it got scrapped i'd probably tear out the engine to use as a coffee table, and use the seat for a gaming rig!)

 

A quick update on this situation...

I've had the car pretty much off the road since this thread was started. Any stop-start journeys were converted to public transport or bike rides, and the 8 only came out for long journeys, or when I was going to have it resting half an hour before starts. Now I want it sorting and back on the road, so a little more information:

I've removed the plugs, and they seem in line with most people's photos - a little beige and black buildup, however the tip of the ground electrode looks to taper in - I'm not sure if this is normal or a worn plug?

It's a 2004 with 28,000 miles, original plugs, coils, and starter.

It refuses to warm start and needs 15 minutes to cool down before starts, which means I go to the petrol station at 2am when it's quiet so I can let it rest.

Perhaps most telling is that if I get a push start before 15 minutes, it will fire up and runs fine. Does this indicate anything on whether that would be a compression issue, or is that bringing us more towards the starter?

So, at this stage I understand we may have eliminated the plugs and coils, right? Cold starts are instant, and the plugs don't look too bad. Someone on another thread mentioned dismantling the starter and using WD40 to spruce it up. Would you recommend this?

How much is a compression test likely to cost? If the result is low compression, how would I fix this? People mention DIY rebuilds, and seafoam (struggling to find a UK alternative), but is this viable in my case with the car only having done 28,000 miles?

I really want to avoid spending £150 on new plugs and coils if its looking unlikely to be those, and I'm happy to strip things down and have a play myself.

Thanks!

 

At 28,000 on the original plugs, wires, and coils, you are due to replace those anyway. Every 30,000 miles is the standard. You won't be throwing money away if you replace them.

However, yes, your symptoms are typical of low compression. In the states, a compression test is anywhere from $90 to $250. I expect that your cost will be whatever is common for 2 hours of diagnostics.

Unlikely that it is your starter, as the starter usually isn't affected by engine temp. If your starter was failing you would have hard cold starts as well. A compression test will give you the cranking RPM, which would confirm whether or not your starter is failing. (anything over about 240rpm is fine, near 300 is great, under 240 is starting to fail, under 210 is on deaths door)


At 28,000 miles, you shouldn't be looking at a failing engine however. The only real reason that comes to mind is that I would suspect that this car never got the MSP-16 update, or got it way too late, and lack of sufficient oil injection is killing your engine the same as early 2004s.

 

Hello, I'm reviving my old thread as the situation has developed... actually I bit the bullet and bought another car to get me through, and now it's 18 months later and the RX8 hasn't budged an inch in that time. Insurance was due and I thought I'd leave it parked and wait for a time (and money) where I could devote to fixing it.

So, I have an RX8 with hot start issues. The battery went flat around a year ago, so it's been sat motionless the whole time. I want to revive it, but I'm not sure how I should go about it. I'm assuming the length of time it's been sat there will necessitate an oil injection of some kind.

The more I've read about it, the more I suspect it could be a carbon issue. It's done ~30K, apparently was used for lots of short journeys before I got it, and I flooded it badly one winter. The last nail in the coffin was when I was doing lots of very short runs (4 mile round trips twice a day) to pick up/drop off my (then) girlfriend.

The problem I have now is that it's not been started in 18 months, and the brakes etc will likely be ceased (they're very oxidised). Also the tyres are cracking. So it can't physically move at the moment, even if it could, it would probably fail its MOT, so I couldn't get it insured to drive it to a get a compression test.

So my new dilemma is this... fix it up (I guess it probably needs new tyres, brakes, engine strip & de-carbon, CAT, battery, coils)... or scrap it.

Does anyone have any advice on viability of the repair? Because it's been sat so long, will it cause me problems in getting it moving?

I suppose I'm not really sure what I want from it any more. I really want it back on the road, but I don't want to go down a long catalogue of repairs that keep adding up. Any advice is really appreciated!

If I removed the engine and stripped it down myself, could it just be a case of cleaning it up?

 

The decision of what to do with it will largely depend on your financial situation, the local market condition for used parts, how much you could get for it unloading it, etc... I can't really offer any advice there.

However, if you do attempt to go start it, remove the plugs first and squirt a bit of ATF into each housing via the lower plug holes. It will help free up the seals and restore the oil film on the housing. It will also give you a big compression jump momentarily to help get the engine started.

Also, keep in mind
- rubber hoses may be cracked, splitting, or fragile.
- Your fuel trims will be gone so idle may have problems.
- Rodents may have moved in as residents somewhere in the car, so check for signs of nesting or whatever, especially in the intake. The air filter is lovely nesting material for them, and you don't want to ingest a mouse nest into the engine when you start it up.
- The fuel is probably pretty poor quality at the moment, and if there is any room in the tank, i recommend getting some fresh fuel to add to help improve the average quality.
- The oil is probably not worth much, so a change should be done first, although this only gets the oil in the pan. Keep in mind that the oil in the coolers is still old, so a 2nd change after you have it running for a bit is probably wise

 

The market for RX8's in the UK is like the oil market now, you can pick up a decent S1 for less than 2000GBP

 

I can only give my perspective.
You seem to be ambivalent about investing more money into it.
You let it sit for very long periods of time, which is one of the worst things you can do to it imo.
You haven't done any significant maintenance that I could tell from your posts.
Lots of stop & go city driving, assuming it hardly ever gets redlined.
In short with the age of all the hoses & lines as RIWWP mentioned, and the history of it, I think you'd be better off parting with it.
An enthusiast may be willing to buy it from you, it would be a shame to 'scrap' it.
If you don't have a real passion for it and take care of it like it should be, then let it go.

 

Thanks guys, you've all pretty much confirmed my thoughts really. I've been fighting for the last 18 months to keep it, thinking that "one day I want this beauty back on the road". I've got new plugs sat in a box waiting to go in, and was pricing up coils, starter, rebuild kit etc, but it was out of budget at the time. I went on holiday, got home and the battery was flat - I'd given my keys to a neighbour to keep the engine ticking over and occasionally redlining it, but judging by the flat battery, this hadn't been done. That was my cue to leave it dormant. I'm in a position where I could now pick up a similar age working RX8 at the book price of around £1500 according to Autotrader. From my calculations, it's going to cost more than that in parts to get it back in fully working order. An insurance company would declare it beyond economical repair.

I did used to take it on a couple of really nice spirited runs every week, but it turned into a "family car" most of the time, solely because my ex didn't drive and we were away from any bus routes.

I'm going to try RIWWP's suggestion to get it back running, and look for a sale. I'd hate to see it scrapped, as I've kept hold of it for 18 months because I didn't always wanted to get it back on the road. If it won't start, it'll be binned as a non-starter... at least if I can get it running it might have a fighting chance!

I'm going to have a look at a few other cars now, with the MX-5 on my shortlist. I'll probably sell/part-ex the Astra and take my time sorting the RX8 for a sale.

 

I'd hate to see anyone who loved their 8 let it go, but it really is a needy mistress.
It's like keeping a spirited colt confined to a barn stall for all it's life.
I know, corny.
I hope you can get it running and make something positive out of the experience, maybe find someone who will restore it to decent working condition
It may not take a lot to revive it, and if you can get a second chance, you may decide to keep it, IF you are willing to treat it the way it was meant to be treated, you may be rewarded for your perseverance.
It really is a fantastic automobile, and if it's within your means, I hope you give it a go.
Good luck!